Accueil >
Production scientifique
Matière Molle
(44) Production(s) de l'année 2021
|
|
Dense Phases of γ-Gliadins in Confined Geometries
Auteur(s): Banc A., Navailles Laurence, Leng Jacques, Renard Denis
(Article) Publié:
Colloids And Interfaces, vol. 5 p.51 (2021)
Texte intégral en Openaccess :
Ref HAL: hal-03443023_v1
DOI: 10.3390/colloids5040051
Exporter : BibTex | endNote
Résumé: The binary phase diagram of γ-gliadin, a wheat storage protein, in water was explored thanks to the microevaporator, an original PDMS microfluidic device. This protein, usually qualified as insoluble in aqueous environments, displayed a partial solubility in water. Two liquid phases, a very dilute and a dense phase, were identified after a few hours of accumulation time in the microevaporator. This liquid–liquid phase separation (LLPS) was further characterized through in situ micro-Raman spectroscopy of the dilute and dense protein phases. Micro-Raman spectroscopy showed a specific orientation of phenylalanine residues perpendicular to the PDMS surfaces only for the diluted phase. This orientation was ascribed to the protein adsorption at interfaces, which would act as nuclei for the growth of dense phase in bulk. This study, thanks to the use of both aqueous solvent and a microevaporator, would provide some evidence for a possible physicochemical origin of the gliadin assembly in the endoplasmic reticulum of albumen cells, leading to the formation of dense phases called protein bodies. The microfluidic tool could be used also in food science to probe protein–protein interactions in order to build up phase diagrams
|
|
Food as complex soft matter physics systems - Is gluten a polymer gel like any others? A journey into the complexity of wheat proteins?
Auteur(s): Ramos L.
Conférence invité: 1st International Seminar on Soft Matter & Food: 1st Polish-Slovenian Edition. Physico-Chemical mode (hybride (Lasek and on-line), PL, 2021-11-22)
|
|
Rheology of model gluten gels
Auteur(s): Ramos L.
Conférence invité: Probing out-of-equilibrium soft matter (Fribourg, CH, 2021-10-22)
|
|
|
Graphite nanoplatelets filled silicone composites with novel electrical and dielectric properties
Auteur(s): Metz R., Blanc C., Prevot G., Hassanzadeh Mehrdad
(Article) Publié:
Journal Of Materials Science-Materials In Electronics, vol. 32 p.26608-26619 (2021)
Texte intégral en Openaccess :
Ref HAL: hal-03419440_v1
DOI: 10.1007/s10854-021-07037-4
WoS: WOS:000704940000007
Exporter : BibTex | endNote
Résumé: In the design of medium and low voltage equipment such as cable accessories, generator, motor end windings or bushings, issues with electrical field enhancement occur at interfaces between insulators and conductors, resulting in accelerated material ageing. The purpose of this paper is to present a novel dielectric composite material which has the properties to mitigate this local amplification. It is a functional dielectric which resistivity decreases by several orders with electric field from 10(14) to 10(9) ohm m up to 1 kV mm(-1) while the dielectric constant decreases from 15 to 12 in the 10(-2)-10(6) Hz range. This novel material is made with graphite nanoplatelets. It may be used as a resistive or capacitive field grading material in electrical applications.
|
|
|
Direct Structural Evidence for Interfacial Gradients in Asymmetric Polymer Nanocomposite Blends
Auteur(s): Genix A.-C., Bocharova Vera, Carroll Bobby, Dieudonne-George P., Sztucki Michael, Schweins Ralf, Sokolov Alexei, Oberdisse J.
(Article) Publié:
Acs Appl. Mater. Interfaces, vol. 13 p.36262-36274 (2021)
Texte intégral en Openaccess :
Ref HAL: hal-03384179_v1
DOI: 10.1021/acsami.1c06971
Exporter : BibTex | endNote
Résumé: Understanding the complex structure of polymer blends filled with nanoparticles (NPs) is the key to designing their macroscopic properties. Here, the spatial distribution of hydrogenated (H) and deuterated (D) polymer chains asymmetric in mass is studied by small-angle neutron scattering. Depending on the chain mass, a qualitatively new large-scale organization of poly(vinyl acetate) chains beyond the random-phase approximation is evidenced in nanocomposites with attractive polymersilica interactions. The silica is found to systematically induce bulk segregation. Only with long H-chains, a strong scattering signature is observed in the q-range of the NP size: it is the sign of interfacial isotopic enrichment, i.e., of contrasted polymer shells close to the NP surface. A quantitative model describing both the bulk segregation and the interfacial gradient (over ca. 10-20 nm depending on the NP size) is developed, showing that both are of comparable strength. In all cases, NP surfaces trap the polymer blend in a non-equilibrium state, with preferential adsorption around NPs only if chain length and isotopic preference towards the surface combine their entropic and enthalpic driving forces. This structural evidence for interfacial polymer gradients will open the road to quantitative understanding of the dynamics of many-chain nanocomposite systems.
|
|
|
Influence of intramolecular charge coupling on intermolecular interactions of polycarboxybetaines in aqueous solution and in polyelectrolyte multilayers
Auteur(s): Schimmel Thomas, Bohrisch Jörg, Anghel Dan, Oberdisse J., von Klitzing Regine
(Article) Publié:
Molecular Physics, vol. 119 p.6722-6733 (2021)
Texte intégral en Openaccess :
Ref HAL: hal-03384120_v1
DOI: 10.1080/00268976.2021.1936676
Exporter : BibTex | endNote
Résumé: The present paper deals with the correlation between intramolecular and intermolecular interactions of polycarboxybetaines. The degree of coupling between the opposite charges within the polycarboxybetaine molecules was varied by spacers of different length and bythe substitution of additional alkyl chains at the quaternary nitrogen atom. In order to check intermolecular interactions between polycarboxybetaines, SANS measurements were carried out at aqueous polycarboxybetaines solutions. For getting information about the interaction with an oppositely charged polyelectrolyte, multilayers were formed by alternating adsorption of polystyrene sulfonate (PSS) and polycarboxybetaines from aqueous solutions. The occurrence of a structure peak in SANS spectra and the ability to form polyelectrolytemultilayers provide an indicator for the polyelectrolyte character of some of the studied polycarboxybetaines. Not only the charge but also the hydrophobicity of the polycarboxybetaines has a pronounced effect on the chain conformation and therefore on the thickness of the polyelectrolyte multilayers. The results show that small differences in molecular architecture lead to pronounced differences in intermolecular interactions.
|